XML无法在marshal上创建JAXBContext [英] XML unable to create JAXBContext on marshal

问题描述

我有一个POJO（在Kotlin中），我想改为XML，但我遇到问题需要通过 JAXBContext.newInstance（myObj :: class.java）部分

I have a POJO(in Kotlin) that I wanted to change into XML but i having problem going through the JAXBContext.newInstance(myObj::class.java) part

只需在Java / Kotlin中查看/回复

这是我的编组上的代码

val context = JAXBContext.newInstance(WxPayOrder::class.java)
val m = context.createMarshaller()

m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true)

val sw = StringWriter()
m.marshal(wxPayOrderWithSign, sw)
val xmlString = sw.toString()

这是我在POJO或数据类上的代码 （我试过这两种情况，无论是否使用
@XmlType& @XmlElement ON）

Here's my code on the POJO or data class (I tried both and neither with/without @XmlType & @XmlElement ON)

@XmlRootElement(name = "WxPayOrder")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = arrayOf("appid","attach","body","detail"))
data class  WxPayOrder (

        @XmlElement(name = "appid")
        var appid: String,

        @XmlElement(name = "attach")
        var attach: String? = null,

        @XmlElement(name = "body")
        var body: String,

        @XmlElement(name = "detail")
        var detail: String? = null,
)

这是我得到的错误（我个人认为）那个信息不够，我看到其他人遇到这个错误也有重复的名字等......但不是我的。）

com.sun.xml.bind.v2.runtime.IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptions
    at com.sun.xml.bind.v2.runtime.IllegalAnnotationsException$Builder.check(IllegalAnnotationsException.java:106)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(JAXBContextImpl.java:471)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:303)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:139)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1156)
    at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:165)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:247)

这是我的pom.xml 的一部分（我只是包含它的一部分因为我害怕我遗漏了一些重要的东西，你们可能会看到它）

Here's my part of my pom.xml (i just include part of it because i scare i left out something important that you guys might able to see it)

<!-- https://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-core -->
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-core</artifactId>
            <version>2.3.0</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/javax.xml.bind/jaxb-api -->
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-impl -->
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.0</version>
        </dependency>

我对Kotlin和JAXB很新。提前致谢。

I'm quite new to Kotlin and JAXB. Thanks in advance.

推荐答案

JAXB需要一个无参数构造函数才能工作。也许你的stacktrace / log中的某个地方也写了......但也许没有。

JAXB requires a no-arg-constructor to work. Maybe somewhere in your stacktrace/log that was also written... but maybe not.

当你使用数据类时，解决问题的最简单方法是添加一个 no-arg-constructor 如下：

As you used a data class, the simplest way to fix the issue is to add a no-arg-constructor as follows:

@XmlRootElement
data class WxPayOrder (
        // all the properties
) {
  // the no-arg-constructor is a must:
  constructor() : this("", body = "", /* all the other properties that must have a value, setting them to a default one */)
}

如果是简单类，你也可以使用类似的东西：

If it was a "simple" class you can also use something similar to:

@XmlRootElement
class WxPayOrder() { // actually now this line contains the no-arg constructor
   // your properties
   lateinit var demo : String
   // your custom constructors
   constructor(demo : String) : this() {
     this.demo = demo
   }
}

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